Microroughness-induced disturbances in supersonic blunt body flow

Schilden, Thomas; Pogorelov, Alexej; Herff, Sohel; Schröder, Wolfgang

doi:10.1103/physrevfluids.5.063903

Cited by 7 publications

(5 citation statements)

References 31 publications

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“…2019; Schilden et al. 2020; Di Giovanni & Stemmer 2018). The boundary layer flow over a blunt body does not support the growth of modal instability waves, and this problem has been termed the ‘blunt-body paradox’.…”

Section: Resultsmentioning

confidence: 98%

“…Another aspect of the flow around a sphere worth examining is the boundary layer transition, which is observed experimentally. Despite substantial recent work on this topic, a theoretical understanding of the boundary layer transition on a blunt body remains elusive (Paredes, Choudhari & Li 2017, 2018Hein et al 2019;Schilden et al 2020;Di Giovanni & Stemmer 2018). The boundary layer flow over a blunt body does not support the growth of modal instability waves, and this problem has been termed the 'blunt-body paradox'.…”

Section: Boundary Layer Transitionmentioning

confidence: 99%

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The influence of hypersonic free-stream conicity on the flow over a sphere

Gu,

Wen,

Hao

et al. 2024

J. Fluid Mech.

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The influence of free-stream conicity on the various aspects of the flow over a spherical test model is examined using both analytical and numerical methods. For the analytical method, a simple closed-form analytical model is assembled. Six different free-stream conditions with different Mach numbers, Reynolds numbers and thermochemistry are tested at four different degrees of conicity corresponding to those which can realistically be encountered in experiments. It is found that the results around the stagnation point are mostly insensitive to the flow condition and gas type, except for some mild non-equilibrium effects, and excellent agreement between the analytical and numerical results exists. The shock stand-off distance on the stagnation streamline is shown to decrease with increasing conicity. This decrease increases the tangential velocity gradient at the stagnation point, increasing the stagnation point heat flux and decreasing the stagnation point boundary layer thickness. The free-stream conicity is also found to alter the normalized distributions of the shock stand-off distance, heat flux, surface pressure and boundary layer thickness with the angle from the stagnation point. In general, increasing the conicity magnifies the slope of these distributions. Regarding the boundary layer transition, it is found that, if it occurs in a uniform free stream, it would also occur in a conical free stream, albeit with the transition point shifted upstream closer to the stagnation point due to the increase in the boundary layer edge tangential velocity. Overall, considering the relevant experimental uncertainties, corrections for free-stream conicity are generally recommended when larger test models are used.

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Section: Resultsmentioning

confidence: 98%

Section: Boundary Layer Transitionmentioning

confidence: 99%

The influence of hypersonic free-stream conicity on the flow over a sphere

Gu,

Wen,

Hao

et al. 2024

J. Fluid Mech.

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“…ZFS is a highly efficient multi-physics simulation framework and developed by the numerical group of the Institute of Aerodynamics and Chair of Fluid Mechanics (AIA), RWTH Aachen University. Flows with shocks were computed for several applications, i.e., a transonic airfoil in [43], a cone in supersonic flow in [48], a blunt stagnation point probe in supersonic flow in [46,47], and a reentry capsule in supersonic flow in [49].…”

Section: Methodsmentioning

confidence: 99%

“…The application of shock AD employing the calculus ( 24) is not straightforward and requires two more steps. To remove the erroneous tangent to the Burgers solution in the vicinity of the shock, we omit the second term on the right-hand side of (24) in the region specified by (49). For the third term, the characteristic function χ has to be evaluated in the discretized computational domain.…”

Section: Tangent Vectors For Burgers Equationmentioning

confidence: 99%

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Algorithmic differentiation of hyperbolic flow problems

Herty,

Hüser,

Naumann

et al. 2020

Preprint

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We are interested in the development of an algorithmic differentiation framework for computing approximations to tangent vectors to scalar and systems of hyperbolic partial differential equations. The main difficulty of such a numerical method is the presence of shock waves that are resolved by proposing a numerical discretization of the calculus introduced in Bressan and Marson [Rend. Sem. Mat. Univ. Padova, 94:79-94, 1995]. Numerical results are presented for the one-dimensional Burgers equation and the Euler equations. Using the essential routines of a state-of-the-art code for computational fluid dynamics (CFD) as a starting point, three modifications are required to apply the introduced calculus. First, the CFD code is modified to solve an additional equation for the shock location. Second, we customize the computation of the corresponding tangent to the shock location. Finally, the modified method is enhanced by algorithmic differentiation. Applying the introduced calculus to problems of the Burgers equation and the Euler equations, it is found that correct sensitivities can be computed, whereas the application of black-box algorithmic differentiation fails.

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